Wait a minute, the OP said it was snowy and icy with a keyword of ROOF. Factor in it's going to be dark out soon from the time you have given.
Would you go on the roof under these circumstances? With all this based on the only option for LOS was the roof with the given facts?
Granted I wasn't there, I don't know if there was actually snow and ice on the roof, but I do know that cold shingles make for no traction add the factor of the pitch of the roof, go from there.
Now that I'm on this, I'll goto say if your house smells like crap due to the wife not picking up the dog poo all over the basement floor and you have a dozen kids running around the half naked constantly in my way from doing my job correctly you can bet I'll drive off and not look back. Yeah I've been there and done installs under those conditions with the customer that demands something for nothing. I love it when people move into there new home and don't bother to mention that they don't even have a tv on site and expect the system to be installed and functioning and want to know how to use it before I leave. It's a real kicker when the husband okay's everything during the walk through, then as your ready to walk out the door with your signed paperwork and wife comes home and starts bitching that she doesn't like where the dish was installed, nor that one tv has be on channel 73 or the universal remote will not work with their television set. Next thing you know you get hit with a trouble call. DING!
I have a very high completion rate on all jobs with very low come backs due to failed equipment, but with out a shadow of a doubt NO tv is worth my safety nor your safety.
Inclinometers are easy to use, you just need to know where your birds sit in the sky, to some they don't want to know how to use it simply because it means they'd have to do the job.
Almost all my installs are right on the ground, where they should be to begin with.
I love my job, I take pride in my work and it shows, I'm not pointing anybody out of crowd but take in the whole picture please.